Mobile devices, such as, for example, cellular radiotelephones, laptops, and personal digital assistants (PDAs), have been increasingly used for viewing multimedia content (e.g., games, movies, music, pictures, etc.). Since the screen display of a mobile device is one of the device components that consume the most electrical power in the mobile device, viewing of multimedia content has increased battery consumption within the mobile devices, decreasing the amount of time a user may use the mobile device on a given charge of the battery.
In order to save battery charge, most mobile devices use “sleep” mode “timeouts” such that after a certain period of time without user activity, the screen display is either turned off or its lighting intensity is reduced. User activity is usually measured on the basis of how long its been since an input device (e.g., mouse, joystick, keyboard, touchpad) has been used. This measurement of user activity is very crude and does not consider that many user activities do not involve “physical” user interaction. For example, viewing pictures or browsing the web on the mobile device are user activities that do not necessarily involve physical user interaction with the mobile device.